Enzyme kinetics in relation to enzyme inhibitors

A Large number of pharmacologically important compounds have been found to act as enzyme inhibitors and a kinetic study of the inhibitory process can provide important information on the potency of the compound and on its mode of interaction with the enzyme. Kinetic studies are generally simple to perform and interpret but their misuse can easily result in erroneous and misleading conclusions. The purpose of this paper is to emphasize the points of kinetic theory that are most frequently misapplied. Since any study of the kinetics of enzyme inhibition will necessarily involve a study of the kinetics of the enzyme in the absence of inhibitor, the first part of this paper deals with such systems. The material discussed in this paper is in no way original and neither does it represent a complete survey of the kinetics of simple enzyme systems; such treatments may be found in a number of textbooks.^1–4 I have chosen to take specific cases in which the enzyme kinetic studies have been frequently misapplied and to illustrate these with reference to the simplest single substrate reaction system. I do not intend to list or give examples of specific errors that have appeared in the literature since the purpose of this paper is not to criticize but to provide information which I hope will lead to a more constructive use of enzyme kinetic studies.